It was not uncommon for the early romantic comedy film to also be a screwball comedy film. This form of comedy film was particularly popular during the 1930s and 1940s. There is no consensus definition of this film style, and it is often loosely applied to slapstick or romantic comedy films. Typically it can include a romantic element, an interplay between people of different economic strata, quick and witty repartee, some form of role reversal, and a happy ending. Some examples of the screwball comedy are: It Happened One Night (1934), Bringing Up Baby (1938), Philadelphia Story (1940), His Girl Friday (1940), and more recently What's Up, Doc? (1972).